The Organic Light Emitting Display (OLED) possesses many outstanding properties of self-illumination, low driving voltage, high luminescence efficiency, short response time, high clarity and contrast, near 180° view angle, wide range of working temperature, applicability of flexible display and large scale full color display. The OLED is considered as the most potential display device.
The OLED can be categorized into two major types according to the driving methods, which are the Passive Matrix OLED (PMOLED) and the Active Matrix OLED (AMOLED), i.e. two types of the direct addressing and the Thin Film Transistor (TFT) matrix addressing. The AMOLED comprises pixels arranged in array and belongs to active display type, which has high lighting efficiency and is generally utilized for the large scale display devices of high resolution.
The present 3T1C pixel driving circuit employed for the OLED comprises a first thin film transistor, a second thin film transistor and a third thin film transistor. The first thin film transistor is a switch thin film transistor, employed for controlling the charge to the organic light emitting diode OLED; the second thin film transistor is a drive thin film transistor; the third thin film transistor is employed for controlling the discharge to the organic light emitting diode OLED. The duration of charge and discharge of sub frames (Subframe) is controlled by controlling the on-periods of the first thin film transistor and the third thin film transistor. With combination that the sense of the human eyes to the brightness is the integral principle of time, the digital voltage (i.e. two Gamma voltages) can be utilized for showing pictures of various gray scale brightnesses.
AS shown in FIG. 1, which is an OLED gate driving circuit structure according to prior art, comprising a gate charge driving circuit, a gate discharge driving circuit, a source driving circuit, and the gate charge driving circuit and the gate discharge driving circuit are respectively located at the left, right two sides of the OLED panel, and the gate charge driving circuit and the gate discharge driving circuit are achieved with different gate driving integrated circuits (IC). The advantage of the OLED gate driving circuit structure is that the well developed driving IC can be utilized.
However, the aforesaid OLED gate driving circuit structure requires two gate driving ICs and the hardware cost is high; meanwhile, the peripheral circuit of the OLED panel is added so that the frame of the panel becomes wider, which increases the technical requirements and the cost.